Liver imaging

The use of LDL and other lipoproteins in drug targeting has been reviewed [170,172], Damle et al. [173] have shown that radiopharmaceuticals, such as iopanoic acid, a cholecystographic agent, could be incorporated in chylomicron remnants by esterification with cholesterol and used for liver imaging. About 87% of the chylomicron remnant-loaded iopanoic acid accumulated in the liver within 0.5 hour after administration, compared with 31% accumulated using a... 

Fig. 13. X-ray crystal structure of complex Gd(III)-76, Na2[Gd(B0PTA)(H20)], an MRI contrast agent on clinical trial for liver imaging. Adapted from (321).

Jaggi, M., Khar, R., Chauhan, U., and Gangal, S. Liposomes as carriers of tech-netium-99m glucoheptonate for liver imaging. Int. J. Pharm. 1991, 69, 77-79. 

Krause W, Mahler M, Hanke B, Milius W, Kaufmann J, Rogalla P, Hamm B (2001) Dy-EOB-DTPA Tolerance and pharmacokinetics in healthy volimteers and preliminary liver imaging in patients. Invest Radiol 36 431... 

Intestinal absorption studies of Mn-MP were undertaken in an effort to assess the viability of the metalloporphyrin as an oral hepatobiliary agent [101, 102]. Mixed micelles of Mn-MP complexed with monoolein and taurocholate were administered to rats, resulting in liver image enhancement 68% above baseline levels six hours after administration [101]. In pigs, the mixed micelle preparation showed variable enhancement over 24 hours. Observation that Mn-MP interacts with oleic acid vesicles [103] led to investigations of the effect of oleic acid on the absorption rate of Mn-MP from the small bowel into the circulatory system [102,104]. The increase in absorption of the complex was mediated by a decrease in the relaxivity of the metalloporphyrin resulting from the interaction with the lipid vesicles. 

The iron(III) tris-complex of Tiron (Fig. 13) has an R, value of 3.15 mM"1 s 1 at 60 MHz and 25 °C [163]. This value is higher than that reported for any other low-molecular weight iron(III) complex [10]. Injection of 0.15 mmol kg-1 into rats demonstrated maximum increases in the kidney and liver image signals of 137% and 73 %, respectively. No toxic effects were seen at this concentration, but all animals injected with 0.3 mmol kg1 of contrast agent died. 

After years of experience with ultrasonography, a well-trained sonographer will produce highly reliable results in the field of liver imaging. The method neither inconveniences nor harms the patient. Thus there is a broad range of indications for examination by ultrasonography in patients with hepatobiliary diseases. There are no contraindications. Specific diagnostic statements, however, are rarely possible. 

Miller, W.J., Dodd, G.D., Federle, M.P., Baron, R.L. Epitheloid hemangioendothelioma of the liver imaging findings with pathologic correlation. Amer. J. Roentg. 1992 159 53-57... 

The Schiff bases derived from pyridoxal and amino acids having the general structure (40) have also been investigated as potential liver imaging agents for use with 553,683-685 com-... 

Write nuclear equations for (a) alpha emission hy polonium-210, used in radiation therapy, (b) beta emission by gold-198, used to assess kidney activity, (c) positron emission by nitrogen-13, used in making brain, heart, and liver images, and (d) electron capture by gallium-67, used to do whole body scans for tumors. 

In addition to B-mode sonography flow-depended techniques such as color-coded duplex sonography or power Doppler sonography can be employed in liver imaging. Although these techniques are used in most cases to obtain information about hepatic vasculature, it has been reported that they also provide additional information on the characterization of focal liver lesions based on their perfusion patterns [39]. 

Extracellular gadolinium-based contrast agents are still highly important in liver imaging. However, there are also tissue-specific contrast agents available, which allow for an increased detection rate and more specific characterization of focal and diffuse liver diseases. 

---